home. We turn to a big medical headline for millions of americans who smoke, even those who quit years ago, sweeping new guidelines anyone has been a heavy smoker will want to paying attention to. Calling for ct scans. I want to bring in dr. Richard besser tonight. How big of a deal is this? It's a big deal. Lung cancer is the number one cancer killer of men and women. Now there is enough evidence that annual ct scans save lives. I always thought they were dangerous. This is limited to those who are the heaviest smokers. People who are 55 and over, smoked a pack a day for at least 30 years, even if you have quit in the past 15 years this is for you. David, tomorrow is new year's eve. This is the time for all smokers to improve their health and say I'm going to quit, get some help and get it done. Rich, thank you. Now to the race car legend

This transcript has been automatically generated and may not be 100% accurate.

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